Genetic engineering of plant chloroplasts

Methods for the transformation of etioplasts and of chloroplasts are disclosed. One method comprises incubating isolated etioplasts with a chelating agent to bind metal ions on which chloroplast nucleases are dependent and incubating the resultant nuclease-inactivated etioplasts with foreign DNA. By an alternative method of transforming chloroplasts, foreign DNA comprising expression cassettes are coated on metal particles and inserted by high-velocity impact into plant cells. For transformation into a plant chloroplast, DNA molecules containing an expression cassette includes a DNA fragment containing appropriate control sequences. The expression cassette may also be flanked by chloroplast DNA which facilitates stable integration of the gene(s) of interest into the recipient chloroplast genome. It is desirable to include within the expression cassette a selectable marker gene that encodes a selectable phenotype which allows for the identification of the cells expressing the introduced gene. Transformed chloroplasts, transformed etioplasts, transformed cells and their progeny, and plants are disclosed. Other aspects of the invention are described